Self-sharpening cutter tip for beater arms of hammer mills



Sept. 4, 1951 J. L. HILLER 2,566,798

SELF-SHARPENING CUTTER TIP FOR BEATER ARMS 0F HAMMER MILLS Filed July 6, 1946 2 Sheet s-Sheet 1 dmy J. L. HILLER 2,566,798

SELF-SHARPENING CUTTER TIP FORBEIATER ARMS OF HAMMER MILLS Sept. 4, 1951 2 Sheets-Sheet 2 Filed July 6, 1946 27221872257: JOSEPH L. .HFLLEE Patented Sept. 4,, 1951 UNITED SELF-SHABPENING CUTTER TIP FOR BEATER ARMS OF HAIVIMEB,

MILLS Joseph L. Hiller, Mattapoisett, Mass.

Application July 6, 1946, Serial No. 681,708

Claims. (01. 241-197) ent No. 1,380,146, dated May 31, 1921, and NO.

1,618,826, dated February 22, 1927. In said patents the cutter tip is a body of substantially regular tetrahedral form, so as to provide, by the intersections of its four substantially triangular faces, a total of six equally-effective cutting edges which, as described in said patent, enable the tip to be used in twelve different working positions, in the beater arm wherein said tip is held; this gives the cutter tip an extremely long life, since it does not need to be discarded and replaced by a new tip until all six of its edges, in succession, have been worn down.

The present invention provides a cutter tip on the same general principles as above set forth, but with the basic tetrahedral body shape so modified by material added and built out in and from the zone of either one or two of the face intersections'as to give a more eflicient utilization of the tip material through the wearing away, in use, of a proportionately larger percentage of its total weight.

Other and further objects and advantages of my invention will be-made apparent from the following detailed description thereof, taken in connection with the accompanying drawings, in

which:

Fig. 1 is a view in side elevation, partly in section, of a hammer mill beater arm and cutter tip, constructed in accordance with my invention.

Fig. 2 is a front view of the assembly of parts shown by Fig. 1.

Fig. 3 is a perspective view of one of my improved cutter tips. I

Fig. 4 is an inner face view of a capping member which is utilized for retaining the cutter tip of Fig. 3 in the beater arm.

Fig. 5 is a front view or said heater arm, on a slightly smaller scale than Fig. 1, showing the socket or recess for receiving said. capping member and the cutter tip of Fig. 3.

Fig. 6 is'a part sectional view of said beater arm, the section being taken on the line 6-6 of Fig. 5.

Figs. 7, 8 and 9 are schematic views illustrating the self-sharpening action incident to progressive wearing away of one of the built out or addendum portions of my improved cutter tip, as obtained, during use of such portion, by successive end-forend reversals thereof in .the beater arm.

Like reference characters refer to like parts in the different figures.

As best shown in Fig. 3, my improved cutter tip is a metal body A whose shape, except as modified and amplified by thickened edgewise extensions of the material as indicated at B and C. is based upon the same regular tetrahedral form that furnishes the cutter tip of my aforesaid two patents. That is to say, my improved cutter tip body A has four primary substantially triangular faces I, 2, 3 and 4, the respective planes of which stand at approximately 70 to each other. The faces I and 2 intersect to provide a wedge-shaped working or cutting edge 5 and a similar edge 6 is formed by the intersection of the faces I and I. Also, the faces 3 and 4 intersect to provide a cutting edge 1, similar in all respects to the cutting edges 5 and 6, as is likewise a fourth cutting edge 8 at the intersection of the faces 2 and 4. These four cutting edges 5, 6, I and 8 correspond, except in the matter of length, to four of the total of six identical edges that are presented by the intersections of the four triangular faces of a regular tetrahedron.

However, it will be noted that my improved cutter tip, asshown by Fig. 3, makes essential departures from such regular tetrahedral shape, in that it does not provide for an edge-forming intersection of its faces I and 4, nor for an edgeforming intersection of its faces 2 and 3. Instead, in the zone where faces I and would normally intersect, the tip material is au mented and built out from both faces to provide a thickened addentum portion B of prismatic shape which contains and encloses the line (indicated by point 9 in Fig. 1) on which the faces I and 4, if extended, would intersect.

In like fashion, in the'zone where faces 2 and 3 would normally intersect, the tip material is built out from both faces vto provide a similar prismatic-shaped thickened addendum portion C which encloses and contains the line (indicated by point II) in Fig. 2) in which said faces 2 and 3, if extended, would intersect.

These two addendumor built out portions B and C are of appreciable thickness and extend appreciably outward from what would be two opposite edges of the basic regular tetrahedral body,

' thus giving my improved cutter tip, in addition to the four conventional cutting edges 5, 6, I, and 8, as mentioned above, a pair of special cutting edges 12 and c that, as hereinafter described in detail, afford a more efiicient and prolonged utilization of the tip material when same are in use. Each portion B and C has a relatively wide upper face II and an opposite somewhat nar 7 (see line I3, Fig. l and line a, Fig. 2 of the basic tetrahedral body, that passes through the aforesaid imaginary lines of face intersection 8 or |||,asthecasemaybe.

Also substantially parallel with the aforesaid central or bisecting plane II are the opposite end faces of addendum portion C-this causinga slight flattening or blunting, as indicated at la and 40, respectively of the contiguous apices' of r the primary cutter tip faces I and 4. Similarly,

the extreme end faces of addendum portion B are made substantially parallel to the other central or bisecting plane Isa, causing a similar slightjtruncation, indicated at 2a and 3a,'respectively, of the other two primary tip faces 2 and 3. Thus in the embodiment of my invention that provides the two addendum portions B and C, all four primary faces of the tip body are substantially identical in size andshape-being of isosceles triangular shape, except for the slight truncations la, 2a, 3a and 4a in the meeting zones of each pair of equal-length sides or edges. The. two spaced-apartsubstantially parallel faces H and I2 of each addendum portion B and C are connected by an outer flat face i4, here shown as extending at an angle of approximately 60 to the plane of the wide face II, this making each addendum portion B and C a substantially chisel-shaped extension of the tip body, presenting an initial cutting edge (I) or c as the case may be) that in working position (see Fig. 1) is slightly ahead of and beyond the line (see 9 Fig.

' 1) on which the tip faces affected by such building out and extension of the tip material would intersect. V The above-described cutter tip body A of modilied and amplified basic tetrahedra1 .form is adapted for association and use with a hammer mill Mater arm designated as a'whole'by the reference character D, said arm having the usual eye-l6 for mounting of the arm on one of the v suspension bars (not shown) of the hammer mill rotor and being thickened at its other end. as shown at IE, to permit the formation of a suitable recess l1 adapted to receive and firmly hold my improved cutter tip A in each of its successive positions of use, as hereinafter described. For that purpose said recess I1 is formedat its lower portion with a suitably sloped end face l8 adapted to be contacted by the tips underneath face (shown as the face 4 in'th tip position of Figs. 1 and 2); and said lower portion of recess I! also presents two opposite inwardly converging side faces II, I! adapted to be contacted by two other tip faces (being the faces 2 and 3 in the tip position of Figs. 1 and 2). These three interior faces ll, l9, l9 are thus in planes that stand at approximately 70 to each other, and their relation to the pivotal mounting of arm D is such as to dispose the tips other or front face (in'this casethe face I) in the nearly radial plane shown as occupied by the front tip faces of my aforesaid two earlier patents-this being approximately the operative position of my im-' addendum portion (see the portion C in Figs. 1

and 2) upon the tip being initially positioned in the recess to expose the other of its addendum portions (see portion B in Figs. 1 and 2) in the operative or exposed position.

The means for clamping and holding my improved cutter tip A in thebeater arm. recess I1 is here shown as a capping member E having an inner tip-engaging portion 2| and an outer portion 22 which provides a flange'22a. The two cap portions 2| and 22 are, spaced apart at their upper ends to form a channel 23 which, with the cap E in operative position (Fig. 1) runs crosswise of the recess I1, and aligns itself with two openings 24, 24 through the opposite side walls of said recesssaid two openings 24, 24 and the cap channel 23 thus providing a passage for the insertion of a removable retaining key 24' by which the assembled cutter tip A and cap E are securely held in the beater arm recess II, with acotter pin 25 to keep the key in place.

The cap portion 2| provides an inner flat surface 30, adapted for frontal contact with the tip A; that is to say, this surface 30 provides extended contact with that face of the tip (the face I in the tip position of Figs. 1 and 2) which is not contacted by the above mentioned recess surfaces I-8 and l9, l9. Extending inwardly from the face 30 are a pair of lateral wings 3|, 3|, in

spaced-apart relation, the opposed inner faces of said wings being undercut as shown at 32, Fig. 4, g

to stand in each instance at an angle of approximately 70 to the face 3|], and at approximately the same angle to each other. Thus, when cap E is seated on tip A, preparatory to insertion of the two parts into beater arm recess I1, said cap makes frontal contact with the tip by its surface 30, and lateral contact therewith by its undercut surfaces 32, 32. The latter, upon the insertion together of tip and cap into recess I], become coplanar substantially with the recess surfaces l9, l9 which'are suitably relieved, as indicated at 33, 33 Figs. 5 and 6, to provide ample room and clearance in the recess for the lower ends of the cap wings 3|, 3|. Also to this end the upper portion of races presents on both sides of channel 20 the relieved portions or lands 35, 35 in opposition to the faces of the wings 3|, 3|. It will further be noted that the caps outer portion 22 adjacent the recess-covering flange 22a provides an interior ledge 33 which, in the assembled position of the parts (see Fig. 1),

enters the upper part of recess 11. and is opposed proved tip, whether its exposed or working edge v be one of the face intersections 5, 6, l, 8 or one of the aforesaid two special dges b, c.

When my improved cutter tip is made with only a single addendum portion (either B or C Fig. 3) there is no need for the recess I! to accommodate initially such an addendum portion, because by the latter's curved upper edge, as indicated at 31.

The cutter tip of my invention, whether it be provided with one addendum portion or two addendum portions, must be initially placed in the beater arm D with one such portion exposed and in the position shown by Fig. 1. In this initial position, which makes a special edge (the edge 1)) operative, the wider face ll of the chisel-shaped extension is always the front or leading face, so that the acute angle cutting edge b is offset forwardly from the central or bisecting plane I} the broken-line hatching 26 of Fig '7, showing that as an accompaniment to such wearing of! of the tip material, there is created on the opposite side of the extension, behind the plane l3, a

new acute angle edge 1). Accordingly, in order to take advantage of this self-sharpening action, produced by initial wearing away of the material of addendum portion 13, the cutter tip body is then removed from the beater arm, and turned end over end relative to addendum portion B so that upon reinsertion with cap E in recess H the tip face 4 will occupy the frontal position previously occupied by the tip .face I this position, with the addendum portion B still presented to the work, but in reversed relation, being represented by Fig. 8. Here, the approximate effect of prolonged use and wear on the material behind the new cutting edge I) is represented by the broken-line hatched area 21, so that as the wear proceeds on the material of addendum portion B another new acute angle cuttingedge I)" is created, again on the opposite side of portion B from the previous working edge I). Thereupon, the cutter tip is again removed from the beater arm, turned over so that the addendum portion is reversed end-for-end in the same manner as before, and re-inserted with the cap E in the beater arm recess I! with its face I again to the front; in this position, as shown by Fig. 9, the new edge b" is presented effectively to the work, for a final wearing away of the remaining material of addendum portion B, as represented by the broken-line cross hatched area 28. Such repeated uses, in the case of a tip having only one addendum portion B or C, serve to condition said tip, by wearing away of practically all of its chisel-shaped protuberance,

for the successive uses thereafter, in the usual manner, of its remaining five wedge-shaped cutting edges, it being evident that none of the latter can be presented in exposed working position in the arm D until the addendum material has been sufliciently dissipated in the manner shown by Figs. 7, 8 and 9 to allow this edge of the tip to be accommodated within the arm recess ll.

Inthe case of a tip having two addendum portions B and C, the same procedure described above of repeated end-for-end reversals of the portion B is thereafter followed with the addendum portion C, in order to take advantage of the self-sharpening action and of the additionally prolonged utilization of tip material afforded by both of these addendum edge portions B and C. When the material of portion C has finally all been substantially dissipated, in approximately the manner indicated by Figs. 7, 8 and 9 for the portion 13, then and only then is the tip in readiness for the successive uses in working position of its normal wedge-shaped cutting edges 5, 6, i and 8, in the manner disclosed by my aforesaid two patents.

I claim:

1. A hammer mill beater arm having a recess, and a cutter tipadapted for retention in said recess in a plurality of different working positions, said cutter tip being constituted by a body portion which is basically and substantially of regular tetrahedral form, to provide a plurality of cutting edges corresponding to certain of the intersectionsof its four primary faces, said body aseeyee portion along the zones of each of two other and opposite face intersections having substantially parallel-sided extensions of'appreciable thickness, each with its free outer end made chisel shaped in section to provide one of the working or cutting edges of said tip, said recess being channeled at its innermost portion to accommodate one of said tip extensions in the tip position which presents the other extension as a working or cutting edge.

2. A hammer mill beater arm having a recess, and a sixedge cutter tip adapted for retention in said recess in a plurality of different working positions, in each of which one such tip edge is operatively exposed, said cutter tip being constituted by a body which is basically and substantially of regular tetrahedral form, to provide by certain of the intersections of its four primary faces, four of said tips cutting edges, said body along the zones of each of its other two face intersections having substantially parallel-slded extensions of appreciable thickness, occupying planes that stand substantially at right angles to each other, and each with its free outer end of chisel-shaped section, to provide said tips two. other working or cutting edges, said recess being channeled at its innermost portion to accommodate one of said extensions in the tip position which presents the other extension as a working or cutting edge.

3. In a hammer mill, a pivoted beater arm having a recess and a multi-edge cutter tip adapted for retention in said recess in a plurality of different working positions, in each of which one of its edges is operatively exposed, said tip being constituted by a body which is basically and substantially of regular tetrahedral form, and presenting a plurality of wedge-shaped cutting edges by certain of the intersections of its four primary faces, said body along the zone of at least one other of said face intersections, being extended outwardly on both sides of a central or bisecting plane which contains the last-named face intersection and stands, in the tip position exposing the end of said extension as the tips cutting edge, at an angle of about 30 with a radial plane containing such intersection and the pivotal axis of said arm. 4. In a hammer mill, a pivoted beater arm having a recess and a multi-edge cutter tip adapted for retention in said recess in a plurality of different working positions, in each of which one of its edges is operatively exposed, said tip bein constituted by a body which is basically and substantially of regular tetrahedral form, and presentin a plurality of wedge-shaped cutting edges by certain of the intersections of its four primary faces, said body along the zone of at least one other of said face intersections, having a substantially parallel-sided outward extension of appreciable thickness, lying on both sides of a central or bisecting plane which contains the last-named face intersection and stands, in the tip position exposing the end of said extension as the tips cutting edge, at an angle of about 30 with a radial plane containing such intersection and the pivotal axis of said arm, the sides of said extension being of unequal width, with the wider side leading, to provide an initial acute angle cutting edge for said tip.

5. In a hammer mill, a pivoted beater arm having a recess and a multi-edge cutter tip adapted for retention in said recess in a plurality of different working positions, in each of which one of its edges is operatively exposed, said tip being other of said face intersections, having a sub-. 5

stantially parallel-sided outward extension of appreciable thickness, lying on both sides of a central or bisecting plane which contains the lastnamed face intersection and stands, in the tip position exposing the end of said extension as the tip's cuttin edge, at an angle of about 30 with a radial plane containing such intersection and the pivotal axis of said arm, the sides of said extension being of unequal width. with the wider side leading, to provide an initial acute angle cutting edge for said tip, said initial cutting edge being in such forwardly offset relation to said central plane that its wearing away in use reduces the width of said leading side to less than that of the other side, thereby creating on said other side a new acute angle cutting edge adapted to be rendered operative by such repositioning of said tip in said recess as to obtain an end-ior-end 8 reversal of said extension in its operatively ex posed position.

JOSEPHVL. mum.

REFERENCES crrnn The following references are of record in the file of this patent:

UNITED s'ra'ms PATENTS Number Name Date 1,041,495 Llggett et al Oct. 15, 1912 1,085,692 Liggett Feb. 3, 1914 1,266,894 Williams May 21, 1918 1,281,829 Plaisted Oct. 15, 1918 1,380,146 Hiller May 31, 1921 1,450,173 Frickey Apr. 3, 1923 1,491,416 Plaisted Apr. 22, 1924 1,618,826 Hiller Feb. 22, 1927 1,669,088 Johnson May 8, 1928 1,693,058 Shelton e Nov. 27, 1928 1,780,247 Simpson Nov. 4, 1930 1,928,516 Van Buskirk Sept. 26, 1933 2,184,123 Mankoif Dec, 19, 1939 

